This invention is in the field of food cooking apparatus and is more particularly directed to the field of deep-fat fryers.
Previously known deep-fat fryers such as those in U.S. Pat. Nos. 3,217,633; 3,217,704; 3,363,541; 3,671,174; 3,712,289, and 3,760,793 have been provided with conventional bunsen burners in which the ambient atmosphere supplies an excess abundance of combustion air with the gaseous products of combustion and excess combustion air being exhausted past the outer surface of the vat to effect a transfer of heat to the vat so as to heat the cooking oil contents thereof. Devices of the foregoing type have proven to be generally satisfactory and have provided an efficiency of approximately 40 percent during normal operation. Although 40 percent efficiency was considered to be satisfactory in the days of abundant and inexpensive combustion gas, the ever increasing cost of combustion gas has in recent years greatly increased the cost of operating such conventional gas burner heated deep-fat fryers.
Another problem with prior known deep fat fryers is that it is necessary to heat all of the cooking oil in the cooking vat in order to cook even small quantities of food so that there is a substantial expense of operation when cooking such small food quantities. Split vat fryers have consequently been sold by a number of manufacturers. However, most restaurants and fast food service outlets have widely fluctuating needs in terms of cooking capacity and it is therefore necessary to have relatively large units which are frequently uneconomical to operate when cooking small quantities of food. It is also well known that different foods require different cooking temperatures and that the same cooking oil should not be used for cooking certain different types of food. Consequently, many commercial establishments find it necessary to have two or more deep fat cooking units or to have large conventional split vat fryers.
Therefore, it is a primary object of this invention to provide a new and improved deep-fat fryer overcoming one or more of the foregoing shortcomings of the prior art devices.
A more specific object of the present invention is to provide a new and improved apparatus and method for cooking with a deep-fat fryer operation heated by gaseous fuel.
Achievement of the foregoing objects is enabled through the preferred embodiment of the invention in which a cooking vat is provided with cooking oil on its interior with pressurized infrared type gas burners adjacent the exterior surface of inwardly facing vertical internal walls of a tunnel extending through the lower portion of the vat for heating the cooking oil contents thereof. The gas burners are connected to a source of pressurized combustion air and a source of combustion gas with the amount of combustion air being metered so as to provide a minimal amount of air substantially no more than that required for efficient combustion of the gas; consequently, the system operates without any substantial amount of excess combustion air absorbing heat from the combustion process so as to reduce the overall efficiency of the system. The specific burner system employed includes two burners each of which has porous ceramic tile members having a large number of small apertures through which the precisely measured mixture of combustion air and gaseous fuel passes for surface combustion adjacent the tile outer surface which faces the inner walls of the vat. The ceramic member is being heated by the combustion so that its outer surface reaches a temperature sufficient to provide radiant heat which impinges on the surface of the inner walls of the vat. Additionally, the gaseous products of combustion are vented along substantial surfaces of the vat so that heat is absorbed from the gaseous products of combustion to provide a further increase in the efficiency of the system.
The vat employed in the preferred embodiment is in the form of an inverted-U-shaped configuration as viewed from the front so as to have two downwardly extending side leg portions between which a tunnel extends from front to rear with the burners being mounted inside the tunnel facing vertical surfaces of the inner walls of the tunnel. A divider consisting of two spaced parallel divider panels divides the vat into two compartments each of which is capable of being heated by one of the two gas burners. It is consequently possible for the vat to be operated at only half of its maximum capacity when only one of the burners is used. It is also possible for both compartments of the vat to be operated at different temperatures. The divider panels are separated by an air space so as to prevent the conductive heat flow from one of the compartments to the other compartment when only one of the compartments is being used. In an alternative embodiment, the divider wall is eliminated so that only a single working compartment is provided.
A better understanding of the different embodiments of the invention will be enabled when the following detailed description is considered in conjunction with the appended drawings in which like reference numerals are used for the same parts of the apparatus as illustrated in the different drawing figures.